1. Field of the Invention
The present invention relates to a flying head slider in general employed in a recording disk drive such as hard disk drive (HDD), and in particular, to a flying head slider comprising a slider body, an air bearing surface (ABS) defined on a medium-opposed surface of the slider body, and a projection defining the tip end higher than the level of the air bearing surface upstream of the air bearing surface.
2. Description of the Prior Art
In the technical field of hard disk drives (HDDs), for example, a so-called contact start stop (CSS) control is well known in which a flying head slider conveying a magnetic read/write head is allowed to be seated on the surface of a magnetic recording disk when the magnetic recording disk stands still. In the CSS control, the seated flying head slider inevitably suffers from adsorption acting from a lubricating agent or oil spread over the surface of the magnetic recording disk. Projections or adsorption prevention pads are thus often formed on the air bearing surface so as to prevent the flying head slider from sticking to the surface of the magnetic recording disk, as is disclosed in Japanese Patent Application Laid-open No. 11-191277, for example. The adsorption prevention pads are designed to reduce the contact area between the flying head slider and the surface of the magnetic, recording disk so as to weaken adsorption acting from the lubricating oil to the flying head slider.
It is a trend in the technical field of HDDs to employ a so-called Hall-less motor as a spindle motor for diving the magnetic recording disk. No Hall element is employed in the Hall-less motor. The Hall-less motor accordingly controls the amount of rotation for the rotor without monitoring or detecting the rotational angle or position of the rotor. The Hall-less motor sometimes suffers from a reverse rotation of the rotation axis when the rotor starts rotating. Such a reverse rotation causes inclination of the flying head slider about the tip ends of the aforementioned adsorption prevention pads on the surface of the magnetic recording disk. The flying head slider is forced to contact the surface of the magnetic recording disk at the outflow or trailing edge in addition to the adsorption prevention pads. The effect of meniscus between the flying head slider and the magnetic recording disk is intensified so that a larger adsorption is induced between the flying head slider and the magnetic recording disk. The magnetic recording disk sometimes cannot even start rotating in this situation, because a recent spindle motor transmits less torque to the magnetic recording disk.
The flying head slier is proposed to comprise depressions on the top or roof surface of the rail so as to narrow the air bearing surface at the trailing edge of the roof surface, as mentioned in Japanese Patent Application Laid-open-No. 11-191277. The depressions are supposed to suppress the effect of meniscus at the trailing edge of the flying head slider when the flying head slider touches the surface of the magnetic recording disk at the trailing edge. However, if the depressions are to be formed on the top surface, an additional process should be included in the production method of the flying head slider. In addition, the flying height of the flying head slider may vary in response to reduction in the area of the air bearing surface. This is not preferable.
It is accordingly an object of the present invention to provide a flying head slider, not only capable of reducing or suppressing adsorption acting from a recording disk when the recording disk stands still, but also capable of contributing to facilitation of its production method.
According to a first aspect of the present invention, there is provided a flying head slider comprising: a slider body having a medium-opposed surface; an air bearing surface defined in the medium-opposed surface; a projection defining a tip end higher than the air bearing surf ace upstream of the air bearing surface; a rail extending over a bottom base of the medium-opposed surface for defining the air bearing surface at its top surface; and a step formed on the top surface of the rail at an upstream end of the air bearing surface, wherein the rail is tapered in a lateral direction of the slider body near an outflow end of the slider body.
For example, in a recording disk or medium drive employing the flying head slider, when a recording disk or medium stands still, the protrusion serves to keep the slider body of the flying head slider above the surface of the recording disk or medium. The air bearing surface is prevented from contacting the surface of the recording disk or medium. The contact area can be reduced between the slider body and the recording disk or medium as compared with the case where the air bearing surface is allowed to contact the surface of the recording disk. The slider body thus receives less adsorption or effect of meniscus from a lubricating oil or other liquid spread over the surface of the recording disk or medium.
Assume that the recording disk makes a reverse rotation. The slider body is supposed to contact the surface of the recording disk at the outflow end or trailing edge of the slier body in addition to the aforementioned projection. However, since the downstream end of the rail is narrowed in the lateral direction, the air bearing surface can also be narrowed near the outflow end of the slider body. Increase in the contact area can be suppressed or prevented between the slide body and the surface of the recording disk. Less adsorption or effect of meniscus is only allowed to act on the slider body from the lubricating oil or other liquid spread over the surface of the recording disk. The adsorption or friction is not intensified between the slider body and the recording disk. Less torque still allows the recording disk to normally start rotating.
After the recording disk has started rotating, the slider body receives, at the medium-opposed surface, air flow generated along the surface of the recording disk. The airflow acts on the step and the air bearing surface in sequence. The step serves to generate a larger lift or positive pressure at the air bearing surface. The lift allows the slider body to fly above the surface of the recording disk. Even if the air bearing surface suffers from reduction in the area in response to the aforementioned narrowed downstream end, the step serves to prevent variation in the lift at the air bearing surface to the utmost.
In general, the flying head slider is figured out of a wafer or other substrate. When the rail is shaped, a resist film is formed on the surface of the substrate for defining the pattern of the rail, for example. Since the rail is narrowed in the above-described manner so as to keep its original thickness or height on the bottom base, it is possible to reduce the area of the air bearing surface near the outflow end of the slider body only by changing the pattern in the resist film. No additional process may be required to form the air bearing surface having the downstream end narrowed in the lateral direction. The production method can be kept simplified irrespective of reduction in the area of the air bearing surface.
According to a second aspect of the present invention, there is provided a flying head slider comprising: a slider body having a medium-opposed surface; a front air bearing surface defined in the medium-opposed surface at an upstream position; a rear air bearing surface defined in the medium-opposed surface at a downstream position; a projection defining a tip end higher than at least the rear air bearing surface upstream of the rear air bearing surface; a rail extending over a bottom base of the medium-opposed surface for defining the rear air bearing surface at its top surface; and a step formed on the top surface of the rail at an upstream end of the rear air bearing surface, wherein the rail is tapered in a lateral direction of the slider body near an outflow end of the slider body.
The front and rear air bearing surfaces are designed to generate lift or positive pressure when the flying head slider receives airflow at the medium-opposed surface. A larger lift can reliably be generated in a relatively facilitated manner. In particular, the flying head slider is preferably allowed to generate negative pressure balanced with the lift or positive pressure at the medium-opposed surface. Such combination of the positive and negative pressures serves to stabilize the flying height of the flying head slider above a recording disk or medium. The flying head slider of the second aspect is adapted to also achieve the advantages similar to those of the above-described flying head slider according to the first aspect.
Furthermore, according to a third aspect of the present invention, there is provided a flying head slider comprising: a slider body having a medium-opposed surface; a primary rail of a predetermined thickness extending over a bottom base of the medium-opposed surface toward an outflow end of the slider body; a slim column designed to stand on the bottom base by a height equal to the predetermined thickness for defining a top surface narrower in a lateral direction of the slider body than a top surface of the primary rail, the slim column continuous to a downstream end of the primary rail; an air bearing surface defined on the top surfaces of the primary rail and slim column; a step defined on the top surface of the primary rail at an upstream end of the air bearing surface; and a projection defining a tip end higher than at least the air bearing surface upstream of the air bearing surface.
The protrusion of this aspect likewise serves to reduce the contact area between the slider body of the flying head slider and the surface of a recording disk or medium in the aforementioned manner as compared with the case where air bearing surface is allowed to contact the surface of the recording disk or medium. The slider body thus receives less adsorption or effect of meniscus from a lubricating oil or other liquid spread over the surface of the recording disk.
Assume that the recording disk makes a reverse rotation. The slider body is supposed to contact the surface of the recording disk at the outflow end or trailing edge of the slider body in addition to the aforementioned projection. However, since the top surface of the slim column, narrower in the lateral direction, is designed to define the air bearing surface near the outflow end of the slider body, the area of the air bearing surface can be reduced near the outflow end. Increase in the contact area can be suppressed or prevented between the slider body and the surface of the recording disk. The adsorption or effect of meniscus is likewise not intensified between the slider body and the recording disk. Less torque still allows the recording disk to normally start rotating.
After the recording disk has started rotating, the slider body receives, at the medium-opposed surface, airflow generated along the surface of the recording disk. The airflow acts on the step and the air bearing surface in sequence. The step serves to generate a larger lift or positive pressure at the air bearing surface. The lift allows the slider body to fly above the surface of the recording disk. Even if the air bearing surface suffers from reduction in the area in response to the aforementioned narrowed downstream end, the step serves to prevent variation in the lift at the air bearing surface to the utmost.
In general, the flying head slider is figured out of a wafer or other substrate. The aforementioned primary rail and the slim column can simultaneously be formed. No additional process may be required to form the air bearing surface having the downstream end narrowed in the lateral direction. The production method can be kept simplified irrespective of reduction in the area of the air bearing surface.
According to a fourth aspect of the present invention, there is provided a flying head slider comprising: a slider body having a medium-opposed surface; a front rail extending over a bottom base of the medium-opposed surface at an upstream position; a front air bearing surface defined on a top surface of the front rail; a primary rear rail of a predetermined thickness extending over a bottom base of the medium-opposed surface at a downstream position; a slim column designed to stand on the bottom base by a height equal to the predetermined thickness for defining a top surface narrower in a lateral direction of the slider body than a top surface of the primary rear rail, the slim column continuous to a downstream end of the primary rear rail; a rear air bearing surface defined on the top surfaces of the primary rear rail and slim column; a step defined on the top surface of the primary rear rail at an upstream end of the rear air bearing surface; and a projection defining a tip end higher than at least the rear air bearing surface upstream of the rear air bearing surface.
The front and rear air bearing surfaces are designed to generate lift or positive pressure when the flying head slider receives airflow at the medium-opposed surface. A larger lift can reliably be generated in a relatively facilitated manner. In particular, the flying head slider is preferably allowed to generate negative pressure balanced with the lift or positive pressure at the medium-opposed surface. Such combination of the positive and negative pressures serves to stabilize the flying height of the flying head slider above a recording disk or medium. The flying head slider of the fourth aspect is adapted to also achieve the advantages similar to those of the above-described flying head slider according to the third aspect.
In any of the aforementioned flying head slider, the projection is preferably designed to stand on a plane which level is lower than the air bearing surface or at least the rear air bearing surface. In these cases, the projection is allowed to have enough height as compared with the case where the projection is designed to stand on the air bearing surface such as the front and rear air bearing surfaces. The higher projection serves to reliably suppress or prevent adsorption or effect of meniscus between the slider body and the surface of the recording disk or medium. On the other hand, a lower projection cannot sufficiently suppress effect of meniscus acting from a lubricating oil or other liquid spread over the surface of the recording disk or medium since the lubricating oil or other liquid is supposed to easily flow upward along the projection until it reaches the slider body.